The basic objective of this research is the elucidation of the mechanism of virus induced neoplastic transformation. The system of Rous sarcoma virus, avian leukosis virus, and chicken cells will be used as a model. We wish to understand the basic mechanism for the genetic interaction between cellular and viral genomes which leads to the generation of oncogenic viruses. In order to understand biochemical basis of cell transformation process induced by avian retroviruses, characterization of products of transforming genes of several sarcoma, and acute leukemia viruses will be made. Finally, we wish to understand the basis of control of expression of viral or cellular src genome by various regulatory elements including viral promoter sequences.